The subject of the present invention is a method for wet flue gas desulfurization in a two-circuit washer having spray apparatus for the absorption agent and a container for the absorption agent, which is based on suspensions containing calcium compounds, whereby the calcium sulfite initially obtained is oxidized by oxygen in the air or by residual oxygen of the flue gas to calcium sulfate, and whereby after the second wash process the absorption agent is at least partially recovered and returned to the container. The present invention furthermore relates to an apparatus for performing this method.
Known from DE 29 44 536 and DE 30 11 592 is a method in which at least part of the used absorption agent of the second (top) cycle is recovered and returned to the absorber reservoir via a recovery and return device and in which the reservoir is arranged adjacent to the washer. In the method and apparatus for performing this method it has been common practice to arrange the container for the absorption agent adjacent to the washer and to supply the spray apparatus from this container.
Known from DE 43 45 364 is returning the used absorption agent of the second (top) cycle in such a two-circuit washer to the container and continuing the reaction between sulfur oxide compounds and calcium compounds there.
Known from DE A 196 01 193 is a method in which the absorption agent is retained in the interior of the washer in a container that is open at its top and the absorption agent is recovered at least in part therein after the washing process, whereby the fluid level in the container is higher than the fluid level in the sump of the washer. All of these methods and apparatus have proven themselves in principle. However, in all of these methods oxidizing the calcium sulfite to calcium sulfate requires additional costs and consumes additional energy.